I tried this approach last week. (Actually, I followed the recipe that Pete-zza had posted a while back which is pretty similar.) After the first 48 hrs, it seemed like things were working. There was a fermenty smell and I was surprised that by the amount of bubbles coming up. Success!
.... Well... I then noticed that my raisins had a small layer of fur on them. I assume this means the bad guys won -- is that true? I tossed it out.
To prepare for this experiment, I had cleaned a glass bowl with hot water. I used California organic grapes, bottled water, and turbinado sugar. I covered it tightly with plastic wrap. I set it in the oven very close (too close?) to the light, with the oven light on the whole time.
What else should I have done? My second-guessings: Should I have rinsed the grapes first? Do I need to sterilize the glass bowl? (Didn't know how to do that -- I didn't want to see the bowl shatter from heat.) Does light affect the process -- should I have kept the bowl further from the light? And I also wonder if was hotter than 80 deg very close to the light. Maybe that sped up / ruined the process.
This was my first attempt with this approach. A while ago, I tried twice to create a starter only from flour, and ended up with the same furries on the dough each time. Argh.
Any help to avoid the furries is appreciated!